Increased cortisol levels – which can occur due to the dysregulation of the HPA axis – can mess with your appetite due to imbalances in the hunger hormone leptin, which has shown to be dysregulated in patients with depression.

“Leptin is the hormone that helps us feel satiety – helps us feel full,” Dr Gadelrab explains. “And as a result of imbalances in this hormone patients can end up overeating or undereating – with typical depression, people will eat less.” Anhedonia – the loss of pleasure – can also play a role here, Dr Gadelrab adds. When food no longer tastes good or brings you joy, your appetite can take a hit, making it harder for people to make filling, nutritious foods and more likely to reach for unhealthy snacks and fast food to supplement their diet.

And then there’s the whole gut-brain axis. If you’ve ever had butterflies in your stomach ahead of a big meeting, you’ll be well aware of the impact your brain can have on gut-related symptoms. But gut-related symptoms can also impact the brain. And scientists have now shown that depression works in this way: a study involving the transplant of faeces from humans with depression into rodents found that those rodents developed depressive symptoms, suggesting that the bacteria found in the guts of depression patients could be having a direct impact on the brain.

Any impact on the gut microbiome can have a wide-reaching impact throughout the body, and that’s the case here, Dr Gadelrab adds. “It can affect the production of serotonin, 95% of which is made in the gut, as well as our circadian rhythm, which can contribute to poor sleep,” she says. “And that can have a knock-on effect on everything from hormone secretion to appetite regulation.”

Depression isn’t just a mental illness – here’s how it affects the body